RMIT-fabricated chip mimics brain’s memory making

Ultra-thin electronic chip an "important step closer to the realisation of a bionic brain" researchers say

Researchers from RMIT, ANU, QUT and Colorado State University have demonstrated an ultra-thin electronic chip which they say can mimic the way neurons work to store and delete information in the brain.

Made from a material called black phosphorus, the researchers have called the chip a breakthrough in neuromorphic computing – which models the nervous system using electronic circuits.

“It brings us an important step closer to the realisation of a bionic brain; a brain-on-a-chip that can learn from its environment just like humans do,” said research team leader Dr Sumeet Walia from RMIT.

Memories begin to be made in the brain when tiny spikes of electrical energy reach a voltage threshold that ‘binds’ a group of neurons. Active connections tend to get stronger, whereas those that aren’t used get weaker and can eventually disappear entirely.

On the chip – described in a paper published today in Advanced Functional Materials – light is used to generate a photocurrent. Switching between colours causes the current to reverse direction from positive to negative.

This direction switch, or polarity shift, is equivalent to the binding and breaking of neural connections, a mechanism that enables neurons to connect and induce learning or inhibit and induce forgetting.

The work was inspired by an emerging tool in biotechnology called optogenetics. Optogenetics uses light to control cells in living tissue, typically neurons, which have been genetically engineered to respond to light. This allows scientists to delve into the body’s electrical system with incredible precision, using light to manipulate neurons so that they can be turned on or off.

“Our optogenetically-inspired chip imitates the fundamental biology of nature’s best computer - the human brain. The translation of biological synapses onto a hardware platform is an important step toward the realisation of brain‐inspired electronics,” said Walia, from RMIT’s Functional Materials and Microsystems Research Group.

“Being able to store, delete and process information is critical for computing, and the brain does this extremely efficiently. We’re able to simulate the brain’s neural approach simply by shining different colours onto our chip,” he said.

The chip-makers used the ‘inherently defective’ nature of black phosphorous to their advantage, they say.

While the defects are usually a problem for optoelectronics, with precision engineering the researchers were able to use them to create new functionality. The chip was fabricated at RMIT’s MicroNano Research Facility.

“Defects are usually looked on as something to be avoided, but here we’re using them to create something novel and useful,” said Dr Taimur Ahmed, lead author of the paper, Multifunctional Optoelectronics via Harnessing Defects in Layered Black Phosphorus.

“It’s a creative approach to finding solutions for the technical challenges we face,” he said.

The technology has potential for use in low-power, wearable electronics, the researchers add, and represents a major step towards “fast, efficient and secure light-based computing”.

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